U.S. patent application number 13/702134 was filed with the patent office on 2013-04-04 for strontium cerate luminescent material and the preparation method and application thereof.
This patent application is currently assigned to OCEAN'S KING LIGHTING SCIENCE & TECHNOLOGY CO., LTD.. The applicant listed for this patent is Jun Liui, Wenbo Ma, Mingjie Zhou. Invention is credited to Jun Liui, Wenbo Ma, Mingjie Zhou.
Application Number | 20130082208 13/702134 |
Document ID | / |
Family ID | 45347634 |
Filed Date | 2013-04-04 |
United States Patent
Application |
20130082208 |
Kind Code |
A1 |
Zhou; Mingjie ; et
al. |
April 4, 2013 |
STRONTIUM CERATE LUMINESCENT MATERIAL AND THE PREPARATION METHOD
AND APPLICATION THEREOF
Abstract
Disclosed is a strontium cerate luminescent material having a
chemical formula of Sr.sub.2CeO.sub.4:xM and comprising the
luminescent material Sr.sub.2CeO.sub.4 and metal nanoparticle M,
and the preparation method thereof, where M is at least one of Ag,
Au, Pt and Pd, and x is a molar ratio of M to the luminescent
material Sr.sub.2CeO.sub.4 and 0<x.ltoreq.1.times.10.sup.-2. The
strontium cerate luminescent material of the present invention,
through doping the luminescent material with metal particles,
improves luminous intensity of the luminescent material by making
use of the surface plasmon resonance generated by surface of the
metal particles; besides, the doped metal ion can improve
electrical conductivity of the luminescent material, and guarantee
that the luminescent material has higher brightness in field
emission devices or LEDs. The preparation method of the present
invention has the advantages of simple operation, no pollution,
easy control, low requirements for equipment, and being favorable
to industrialized production.
Inventors: |
Zhou; Mingjie; (Guangdong,
CN) ; Liui; Jun; (Guangdong, CN) ; Ma;
Wenbo; (Guangdong, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zhou; Mingjie
Liui; Jun
Ma; Wenbo |
Guangdong
Guangdong
Guangdong |
|
CN
CN
CN |
|
|
Assignee: |
OCEAN'S KING LIGHTING SCIENCE &
TECHNOLOGY CO., LTD.
GUANGDONG
CN
|
Family ID: |
45347634 |
Appl. No.: |
13/702134 |
Filed: |
June 17, 2010 |
PCT Filed: |
June 17, 2010 |
PCT NO: |
PCT/CN2010/074030 |
371 Date: |
December 5, 2012 |
Current U.S.
Class: |
252/301.4R ;
264/21; 977/773; 977/896 |
Current CPC
Class: |
Y10S 977/773 20130101;
C09K 11/873 20130101; C09K 11/7718 20130101; C09K 11/87 20130101;
Y10S 977/896 20130101; B82Y 40/00 20130101 |
Class at
Publication: |
252/301.4R ;
264/21; 977/773; 977/896 |
International
Class: |
C09K 11/87 20060101
C09K011/87; C09K 11/77 20060101 C09K011/77 |
Claims
1. A strontium cerate luminescent material, having a chemical
formula of Sr.sub.2CeO.sub.4:xM, the strontium cerate luminescent
material comprises luminescent material Sr.sub.2CeO.sub.4 and metal
nanoparticle M, where M is at least one of Ag, Au, Pt and Pd, and x
is a molar ratio of M to the luminescent material Sr.sub.2CeO.sub.4
and 0<x.ltoreq.1.times.10.sup.-2.
2. The strontium cerate luminescent material according to claim 1,
characterized in that
1.times.10.sup.-5.ltoreq.x.ltoreq.1.times.10.sup.-3.
3. An application of the strontium cerate luminescent material
according to claim 1 used as a blue luminescent material in a field
emission light-emitting device or an LED.
4. A preparation method of the strontium cerate luminescent
material, comprising: S1, mixing a metal compound solution, an
assistant for stable dispersion and a reductant solution, and
stirring to react to produce a metal nanoparticle sol, where the
metal nanoparticle is at least one of Ag, Au, Pt, Pd and Cu; S2,
adding an Sr salt solution and a Ce salt solution of a desired
amount into anhydrous ethanol according to a ratio as shown by the
chemical formula Sr.sub.2CeO.sub.4:xM, adding a complexing agent
and a dispersing agent, and stirring sufficiently to obtain a mixed
solution; M is the metal nanoparticle, and x is a molar ratio of M
to the luminescent material Sr.sub.2CeO.sub.4 and
0<x.ltoreq.1.times.10.sup.-2; and S3, adding the metal
nanoparticle sol into the mixed solution, stirring to react to
obtain a strontium cerate luminescent material sol, and then drying
the strontium cerate luminescent material sol before heating to
produce the desired strontium cerate luminescent material.
5. The method of preparation of the strontium cerate luminescent
material according to claim 4, characterized in that the assistant
has a concentration of
1.5.times.10.sup.-4.about.2.1.times.10.sup.-3 g/mL in the metal
nanoparticle sol; the reductant solution has a concentration of
1.times.10.sup.-3.about.1.times.10.sup.-2 mol/L, and an amount
ratio of the reductant to the metal nanoparticle is from 1.2:1 to
4.8:1.
6. The method of preparation of the strontium cerate luminescent
material according to claim 4, characterized in that the metal
compound is selected from at least one of the group consisting of
AgNO.sub.3, AuCl.sub.3.HCl.4H.sub.2O, H.sub.2PtCl.sub.6.6H.sub.2O,
and PdCl.sub.2.2H.sub.2O; the assistant is selected from at least
one of the group consisting of polyvinylpyrrolidone, sodium
citrate, cetyl trimethylammonium bromide, sodium lauryl sulfate and
sodium dodecanesulphonate; and the reductant is selected from at
least one of the group consisting of hydrazine hydrate, ascorbic
acid and sodium borohydride.
7. The method of preparation of the strontium cerate luminescent
material according to claim 4, characterized in that it further
comprises steps of surface treating the obtained metal nanoparticle
sol, which are specifically as follows: adding a desired amount of
a surface treatment agent into the metal nanoparticle sol according
to volume of the metal nanoparticle sol, and stirring at room
temperature for 3.about.24 h to make the surface treatment agent
have a concentration of 0.0010.about.1 g/mL in the final sol.
8. The method of preparation of the strontium cerate luminescent
material according to claim 7, characterized in that the surface
treatment agent is polyvinylpyrrolidone.
9. The method of preparation of the strontium cerate luminescent
material according to claim 4, characterized in that the Sr salt is
Sr(NO.sub.3).sub.2, and the Ce salt is Ce(NO.sub.3).sub.3; the
complexing agent is citric acid monohydrate, a ratio of which to a
molar sum of Sr and Ce is from 1:1 to 3:1; and the dispersing agent
is polyethylene glycol.
10. The method of preparation of the strontium cerate luminescent
material according to claim 4, characterized in that the heat
treatment comprises presintering and calcining, with a presintering
temperature at 500.degree. C..about.800.degree. C. and a
presintering duration of 2.about.7 h, and a calcining temperature
at 800.degree. C..about.1300.degree. C. and a calcining duration of
2.about.6 h.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of luminescent
material and illumination technology, and particularly to a
strontium cerate luminescent material and the preparation method
and application thereof
BACKGROUND OF THE INVENTION
[0002] There are mainly two types of conventional commercial field
emission (FED) luminescent materials, the sulfide system and the
oxide system. The sulfide system includes blue powder ZnS:AgCl and
SrGa.sub.2S.sub.4:Ce, green powder SrGa.sub.2S.sub.4:Eu and red
powder Y.sub.2O.sub.2S:Eu. The fluorescent powder of the sulfide
series has higher luminous efficiency but poor stability, easy to
decompose to produce sulphur under the low-voltage large-current
electron beam bombardment, which makes the properties of the
material itself deteriorate on one hand and the cathode electron
emission needle seriously "poisoned" by sulphur on the other hand.
The oxide system mainly includes blue powder Y.sub.2SiO.sub.5:Ce,
green powder ZnGa.sub.2O.sub.4:Mn, Y.sub.2SiO.sub.5:Tb and
Y.sub.3Al.sub.5O.sub.12:Tb, and red powder Y.sub.2O.sub.3:Eu. The
fluorescent powder of the oxide series has higher stability, but
not sufficiently high luminous efficiency under the low-voltage
electron beam bombardment; and all the fluorescent powder of the
oxide series is an insulator, making its use in the FED device
subject to certain restrictions.
SUMMARY OF THE INVENTION
[0003] Thus it is necessary to provide a strontium cerate
luminescent material having good stability and high luminous
efficiency.
[0004] A strontium cerate luminescent material is provided, having
a chemical formula of Sr.sub.2CeO.sub.4:xM and comprising the
luminescent material Sr.sub.2CeO.sub.4 and the metal nanoparticle
M, where M is at least one of Ag, Au, Pt and Pd, and x is a molar
ratio of M to the luminescent material Sr.sub.2CeO.sub.4 and
0<x.ltoreq.1.times.10.sup.-2. Preferably, x is in the range of
1.times.10.sup.-5.ltoreq.x.ltoreq.1.times.10.sup.-3.
[0005] The strontium cerate having the above chemical structure can
be used as the blue luminescent material in the field emission
light-emitting device or LED.
[0006] In addition, it is necessary to provide a method of
preparation of the strontium cerate luminescent material having
good stability and high luminous efficiency.
[0007] A preparation method of the strontium cerate luminescent
material is provided, comprising: S1, mixing a metal compound
solution, an assistant for stable dispersion and a reductant
solution, and stirring to react to produce a metal nanoparticle
sol, where the metal nanoparticle is at least one of Ag, Au, Pt, Pd
and Cu; S2, adding an Sr salt solution and a Ce salt solution of a
desired amount into anhydrous ethanol according to a ratio as shown
by the chemical formula Sr.sub.2CeO.sub.4:xM, adding a complexing
agent and a dispersing agent, and stirring sufficiently to produce
a mixed solution; M is the above metal nanoparticle, and x is a
molar ratio of M to the luminescent material Sr.sub.2CeO.sub.4 and
0<x.ltoreq.1.times.10.sup.-2; S3, adding the metal nanoparticle
sol into the above mixed solution, and stirring to react to obtain
a strontium cerate luminescent material sol, and then drying before
heat treatment to produce the desired strontium cerate luminescent
material.
[0008] Preferably, the assistant has a concentration of
1.5.times.10.sup.-4.about.2.1.times.10.sup.-3 g/mL in the metal
nanoparticle sol; the reductant solution has a concentration of
1.times.10.sup.-3.about.1.times.10.sup.-2 mol/L, and the amount
ratio of the reductant to the metal nanoparticle is from 1.2:1 to
4.8:1.
[0009] Preferably, the metal compound is selected from at least one
of the group consisting of AgNO.sub.3, AuCl.sub.3.HCl.4H.sub.2O,
H.sub.2PtCl.sub.6.6H.sub.2O and PdCl.sub.2.2H.sub.2O; the assistant
is selected from at least one of the group consisting of
polyvinylpyrrolidone, sodium citrate, cetyl trimethylammonium
bromide, sodium lauryl sulfate and sodium dodecanesulphonate; and
the reductant is selected from at least one of the group consisting
of hydrazine hydrate, ascorbic acid and sodium borohydride.
[0010] Preferably, the method further includes steps of surface
treatment on the obtained metal nanoparticle sol, which are
specifically as follows: adding a desired amount of the surface
treatment agent into the metal nanoparticle sol according to the
volume of the metal nanoparticle sol, and stirring at room
temperature for 3.about.24 h to make the surface treatment agent
have a concentration of 0.001-0.1 g/mL in the final sol.
[0011] Preferably, the surface treatment agent is
polyvinylpyrrolidone.
[0012] Preferably, the Sr salt and the Ce salt are Sr(NO.sub.3),
and Ce(NO.sub.3).sub.3, respectively; the complexing agent is
citric acid monohydrate, a ratio of which to a molar sum of Sr and
Ce is from 1:1 to 3:1; and the dispersing agent is polyethylene
glycol.
[0013] Preferably, the heat treatment includes presintering and
calcining, with a presintering temperature at 500.degree.
C..about.800.degree. C. and a presintering duration of 2.about.7 h,
and a calcining temperature at 800.degree. C..about.1300.degree. C.
and a calcining duration of 2.about.6 h.
[0014] The above strontium cerate luminescent material of the oxide
system has good stability and, with the luminescent material doped
with metal particles, improved luminous intensity by making use of
the surface plasmon resonance generated by surface of the metal
particles; besides, the doped metal ion can improve electrical
conductivity of the luminescent material, and guarantee that the
luminescent material has higher brightness in field emission
devices or LED.
[0015] In addition, the strontium cerate luminescent material
prepared by the above method has stable properties and high
luminous efficiency, and the preparation method has the advantages
of simple operation, no pollution, easy control, low requirements
for equipment, and being favorable to industrialized
production.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a comparison diagram of the luminescent spectra of
the luminescent materials prepared in Example 3 under the cathode
ray excitation with an acceleration voltage of 1.5 kV, where the
curve a is the emission spectrum of the
Sr.sub.2CeO.sub.4:5.times.10.sup.-5 Ag luminescent material with
the addition of Ag nanoparticles, and the curve b is the emission
spectrum of the Sr.sub.2CeO.sub.4 luminescent material without the
addition of Ag metal nanoparticles.
[0017] FIG. 2 is a comparison diagram of the emission spectra of
the luminescent materials prepared in Example 3 (having an
excitation wavelength of 347 nm), where the curve c is the emission
spectrum of the luminescent material
Sr.sub.2CeO.sub.4:5.times.10.sup.-5 Ag, and the curve d is the
emission spectrum of the luminescent material
Sr.sub.2CeO.sub.4.
[0018] FIG. 3 is a comparison diagram of the excitation spectra of
the luminescent materials prepared in Example 3 (having a
monitoring wavelength of 475 nm), where the curve e is the
excitation spectrum of the luminescent material
Sr.sub.2CeO.sub.4:5.times.10.sup.-5 Ag, and the curve f is the
excitation spectrum of the luminescent material
Sr.sub.2CeO.sub.4.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] Through the addition of metal nanoparticles into the
luminescent material, the luminous intensity of the luminescent
material is improved by making use of the surface plasmon (SP)
resonance effect generated by the surface of metal nanoparticles.
The surface plasmon produced by the surface of metal nanoparticles
is a wave propagating along an interface between a metal and a
medium, whose amplitude is damped exponentially with the distance
away from the interface. When the luminescent material is doped
with metal particles, the property, dispersion relation, excitation
mode, coupling effect and the like of the surface plasmon
polaritons (SPPs) will be changed significantly. The
electromagnetic field caused by SPPs can not only limit propagation
of a light wave in a sub-wavelength sized structure, but also
produce and control electromagnetic radiation from the optical
frequencies to the microwave region, realizing active control of
the light propagation, thus increasing optical state density and
spontaneous radiation velocity of the luminescent material.
Besides, the internal quantum efficiency of the luminescent
material can be improved greatly by making use of the coupling
effect of the surface plasmon, thus improving the luminous
intensity of the luminescent material.
[0020] In the following is provided the strontium cerate
luminescent material used as the blue luminescent material in the
field emission light-emitting device (FED) or LED, which has a
chemical formula of Sr.sub.2CeO.sub.4:xM and comprises the
luminescent material Sr.sub.2CeO.sub.4 and the metal nanoparticle
M, where M is at least one of Ag, Au, Pt and Pd, and x is a molar
ratio of M to the luminescent material Sr.sub.2CeO.sub.4 and
0<x.ltoreq.1.times.10.sup.-2. Preferably, x is in the range of
1.times.10.sup.-5.ltoreq.x.ltoreq.1.times.10.sup.-3.
[0021] The above M is doped in the luminescent material
Sr.sub.2CeO.sub.4 in a form of metal nanoparticles, and enhances
the luminous intensity of the luminescent material
Sr.sub.2CeO.sub.4 through the surface plasmon resonance effect
generated by the surface of metal nanoparticles.
[0022] In addition, a method of preparation of the strontium cerate
luminescent material is provided, comprising: first preparing the
metal nanoparticle sol, and then preparing the strontium cerate
luminescent material by mixing Sr(NO.sub.3).sub.2 and
Ce(NO.sub.3).sub.3 according to the proportional relation between
the metals as shown in the chemical formula. The method is
specifically as follows:
[0023] I. Preparation of the Metal Nanoparticle Sol:
[0024] 1) Preparing a metal compound solution, where the metal
compound is at least one of AgNO.sub.3, AuCl.sub.3.HCl.4H.sub.2O,
H.sub.2PtCl.sub.6.6H.sub.2O and PdCl.sub.2.2H.sub.2O, and the
solvent is water or ethanol;
[0025] 2) dissolving one or more assistants into the above metal
compound solution obtained in A1) under the magnetic stirring
condition, making the assistant(s) have a concentration of
1.5.times.10.sup.-4-2.1.times.10.sup.-3 g/mL in the final metal
nanoparticle sol; the assistant is preferably polyvinylpyrrolidone,
sodium citrate, cetyl trimethylammonium bromide, sodium lauryl
sulfate or sodium dodecanesulphonate;
[0026] 3) preparing a reductant solution at a concentration range
of 1.times.10.sup.-3-1.times.10.sup.-2 mol/L; the reductant is at
least one of hydrazine hydrate, ascorbic acid and sodium
borohydride, and the solvent is water or ethanol; and
[0027] 4) adding the above reductant solution of A3) into the
solution containing the assistant(s) obtained in the above A2)
under the magnetic stirring condition in an amount ratio of the
reductant to the metal ion from 1.2:1 to 4.8:1, and reacting for 10
min -45 min to obtain the metal nanoparticle sol.
[0028] Preferably, the metal nanoparticle further needs surface
treatment, which is specifically as follows: putting a certain
amount of surface treatment agent into the metal nanoparticle sol
according to the volume of the metal nanoparticle sol, and stirring
at room temperature for 3 h-24 h to make the surface treatment
agent have a concentration of 0.001 g/mL-0.1 g/mL in the final sol;
and the surface treatment agent is preferably
polyvinylpyrrolidone.
[0029] II. Preparation of the Strontium Cerate Luminescent Material
With a Chemical Formula of Sr.sub.2CeO.sub.4:xM:
[0030] 1) Adding a certain volume of Sr(NO.sub.3).sub.2 solution
and Ce(NO.sub.3).sub.3 solution into a beaker according to the
chemical formula of Sr.sub.2CeO.sub.4:xM, then adding anhydrous
ethanol, and stirring sufficiently to obtain a mixed nitrate
solution;
[0031] 2) adding a complexing agent and a dispersing agent into the
above obtained mixed nitrate solution, and stirring sufficiently,
where the complexing agent is preferably citric acid, and
specifically citric acid monohydrate, a molar ratio of which to the
total metal ions in the mixed solution is from 1:1 to 3:1, and the
dispersing agent is preferably polyethylene glycol;
[0032] 3) adding the metal nanoparticle sol into the solution
obtained in the above step B2), heating and stirring at 70.degree.
C.-90.degree. C. in a water bath for 2-6 h to obtain a strontium
cerate luminescent material sol; and drying the strontium cerate
luminescent material sol at 80.degree. C.-150.degree. C. completely
to produce the precursor; and
[0033] 4) putting the precursor in a high temperature furnace,
presintering at 500.degree. C.-800.degree. C. for 2-7 h, cooling to
the room temperature, and grinding; then putting it in a box type
high temperature furnace or tubular furnace, calcining at
800.degree. C.-1300.degree. C. for 2-6 h, naturally cooling, and
grinding to produce the strontium cerate luminescent material with
a chemical formula of Sr.sub.2CeO.sub.4:xM.
[0034] The above strontium cerate luminescent material and the
preparation method and luminescent property thereof will further be
described below with reference to specific examples.
EXAMPLE 1
[0035] Preparation of the Pt nanoparticle sol: Weighing 5.18 mg
chloroplatinic acid (H.sub.2PtCl.sub.6.6H.sub.2O) to dissolve into
17 mL deionized water to obtain the chloroplatinic acid aqueous
solution; after chloroplatinic acid is completely dissolved,
weighing 8.0 mg sodium citrate and 12.0 mg sodium
dodecanesulphonate, and dissolving into the chloroplatinic acid
aqueous solution under the magnetic stirring condition; weighing
0.38 mg sodium borohydride to dissolve into 10 mL deionized water
to obtain 10 mL sodium borohydride aqueous solution at a
concentration of 1.times.10.sup.-3 mol/L, and meanwhile preparing
10 mL hydrazine hydrate solution at a concentration of
1.times.10.sup.-2 mol/L; under the magnetic stirring condition,
first dropwise adding 0.4 mL sodium borohydride aqueous solution
into the chloroplatinic acid aqueous solution and stirring to react
for 5 min, then dropwise adding 2.6 mL 1.times.10.sup.-2 mol/L
hydrazine hydrate solution into the chloroplatinic acid aqueous
solution, and then continuing to react for 40 min to obtain 20 mL
Pt nanoparticle sol with the Pt concentration at 5.times.10.sup.-4
mol/L; then adding 2 g PVP into the Pt nanoparticle sol, and
magnetically stirring for 12 h to produce the Pt nanoparticle
having been subject to the surface treatment.
[0036] Preparation of 0.001 mol
Sr.sub.2CeO.sub.4:1.times.10.sup.-2Pt: Putting 1 mL 2 mol/L
Sr(NO.sub.3).sub.2 solution and 1 mL 1 mol/L Ce(NO.sub.3).sub.3
solution into a beaker, then adding 10 mL ethanol, and stirring
sufficiently to obtain a mixed nitrate solution; adding into this
mixed solution 0.63042 g citric acid (the molar ratio of the added
citric acid to the total metal ions in the mixed solution is 1:1)
and 1 g PEG (polyethylene glycol), and stirring sufficiently;
taking 20 mL of the above metal particle solution having been
processed, and heating and stirring at 70.degree. C. in a water
bath for 6 h to produce a sol; drying the sol completely at
80.degree. C. to produce the precursor; putting this precursor in a
high temperature furnace, presintering at 500.degree. C. for 7 h,
cooling to the room temperature, and grinding; then putting it in a
box type high temperature furnace or tubular furnace, calcining at
800.degree. C. for 6 h, naturally cooling, and grinding to produce
the Sr.sub.2CeO.sub.4:1.times.10.sup.-2Pt luminescent material.
EXAMPLE 2
[0037] Preparation of the Au nanoparticle sol: Weighing 4.12 mg
chloroauric acid (AuCl.sub.3.HCl.4H.sub.2O) to dissolve into 8.4 mL
deionized water to obtain the chloroauric acid aqueous solution;
after chloroauric acid is completely dissolved, weighing 14 mg
sodium citrate and 6 mg cetyl trimethylammonium bromide, and
dissolving into the chloroauric acid aqueous solution under the
magnetic stirring condition; weighing 1.9 mg sodium borohydride and
17.6 mg ascorbic acid to dissolve into 10 mL deionized water,
respectively, to obtain 10 mL sodium borohydride aqueous solution
at a concentration of 5.times.10.sup.-3 mol/L and 10 mL ascorbic
acid aqueous solution at a concentration of 1.times.10.sup.-2
mol/L; under the magnetic stirring condition, first adding 0.04 mL
sodium borohydride aqueous solution into the chloroauric acid
aqueous solution, stirring to react for 5 min, then adding 1.56 mL
1.times.10.sup.-2 mol/L ascorbic acid aqueous solution into the
chloroauric acid aqueous solution, and then continuing to react for
30 min to obtain 10 mL Au nanoparticle sol with the Au
concentration at 1.times.10.sup.-3 mol/L; then taking 6 mL of the
obtained Au nanoparticle sol, adding 0.006 g PVP into the Au
nanoparticle sol, and magnetically stirring for 8 h to produce the
Au nanoparticle having been subject to the surface treatment.
[0038] Preparation of 0.01 mol
Sr.sub.2CeO.sub.4:5.times.10.sup.-4Au: Putting 10 mL 2 mol/L
Sr(NO.sub.3).sub.2 solution and 10 mL 1 mol/L Ce(NO.sub.3).sub.3
solution into a beaker, then adding 20 mL ethanol, and stirring
sufficiently to obtain a mixed nitrate solution; adding into this
mixed solution 12.6084 g citric acid (the molar ratio of the added
citric acid to the total metal ions in the mixed solution is 2:1)
and 1 g PEG (polyethylene glycol), and stirring sufficiently;
taking 5 mL of the above metal particle solution having been
processed, and heating and stirring at 80.degree. C. in a water
bath for 4 h to produce a sol; drying the sol completely at
100.degree. C. to produce the precursor; putting this precursor in
a high temperature furnace, presintering at 700.degree. C. for 5 h,
cooling to the room temperature, and grinding; then putting it in a
box type high temperature furnace or tubular furnace, calcining at
1000.degree. C. for 4 h, naturally cooling, and grinding to produce
the Sr.sub.2CeO.sub.4:5.times.10.sup.-4Au luminescent material.
EXAMPLE 3
[0039] Preparation of the Ag nanoparticle sol: Weighing 3.40 mg
silver nitrate (AgNO.sub.3) to dissolve into 18.4 mL deionized
water to obtain the silver nitrate aqueous solution; after silver
nitrate is completely dissolved, weighing 22 mg sodium citrate and
20 mg PVP, and dissolving into the silver nitrate aqueous solution
under the magnetic stirring condition; weighing 5.7 mg sodium
borohydride to dissolve into 10 mL deionized water to obtain 10 mL
sodium borohydride aqueous solution at a concentration of
1.5.times.10.sup.-2 mol/L; adding 1.6 mL 1.5.times.10.sup.-2 mol/L
sodium borohydride aqueous solution into the silver nitrate aqueous
solution at one time under the magnetic stirring condition, and
then continuing to react for 10 min to obtain 20 mL Ag nanoparticle
sol with the Ag concentration at 1.times.10.sup.-3 mol/L; adding 1
g PVP into the Ag nanoparticle sol, and magnetically stirring for 6
h to produce the Ag nanoparticle having been subject to the surface
treatment.
[0040] Preparation of 0.01 mol
Sr.sub.2CeO.sub.4:5.times.10.sup.-5Ag: Putting 10 mL 2 mol/L
Sr(NO.sub.3).sub.2 solution and 10 mL 1 mol/L Ce(NO.sub.3).sub.3
solution into a beaker, then adding 20 mL ethanol, and stirring
sufficiently to obtain a mixed nitrate solution; adding into this
mixed solution 12.6084 g citric acid (the molar ratio of the added
citric acid to the total metal ions in the mixed solution is 2:1)
and 1 g PEG (polyethylene glycol), and stirring sufficiently;
taking 0.5 mL of the above metal particle solution having been
processed, and heating and stirring at 85.degree. C. in a water
bath for 5 h to produce a sol; drying the sol completely at
120.degree. C. to produce the precursor; putting this precursor in
a high temperature furnace, presintering at 800.degree. C. for 2 h,
cooling to the room temperature, and grinding; then putting it in a
box type high temperature furnace or tubular furnace, calcining at
1200.degree. C. for 4 h, naturally cooling, and grinding to produce
the Sr.sub.2CeO.sub.4:5.times.10.sup.-5Ag luminescent material.
Preparing the Sr.sub.2CeO.sub.4 luminescent material by the same
method.
[0041] FIG. 1 is a comparison diagram of the luminescent spectra of
the luminescent materials prepared in Example 3 under the cathode
ray excitation with an acceleration voltage of 1.5 kV, where the
curve a is the emission spectrum of the
Sr.sub.2CeO.sub.4:5.times.10.sup.-5Ag luminescent material with the
addition of Ag nanoparticles, and the curve b is the emission
spectrum of the Sr.sub.2CeO.sub.4 luminescent material without the
addition of Ag metal nanoparticles. It can be seen from FIG. 1 that
this luminescent material is blue-light luminescent material, and
luminous intensity of the sample can be improved by 1.5 times after
metal doping.
[0042] FIG. 2 is a comparison diagram of the emission spectra of
the luminescent materials prepared in Example 3 (having an
excitation wavelength of 347 nm), where the curve c is the emission
spectrum of the luminescent material
Sr.sub.2CeO.sub.4:5.times.10.sup.-5Ag, and the curve d is the
emission spectrum of the luminescent material Sr.sub.2CeO.sub.4. It
can be seen from FIG. 2 that the luminous intensity can be improved
by 1.5 times after metal doping.
[0043] FIG. 3 is a comparison diagram of the excitation spectra of
the luminescent materials prepared in Example 3 (having a
monitoring wavelength of 475 nm), where the curve e is the
excitation spectrum of the luminescent material
Sr.sub.2CeO.sub.4:5.times.10.sup.-5Ag, and the curve f is the
excitation spectrum of the luminescent material Sr.sub.2CeO.sub.4.
It can be seen from FIG. 3 that this luminescent material can be
used in LED.
EXAMPLE 4
[0044] Preparation of the Pd nanoparticle sol: Weighing 0.43 mg
palladium chloride (PdCl.sub.2.2H.sub.2O) to dissolve into 8.5 mL
deionized water to obtain the palladium chloride aqueous solution;
after palladium chloride is completely dissolved, weighing 11.0 mg
sodium citrate and 4.0 mg sodium lauryl sulfate, and dissolving
into the palladium chloride aqueous solution under the magnetic
stirring condition; weighing 3.8 mg sodium borohydride to dissolve
into 10 mL deionized water to obtain a sodium borohydride reducing
solution at a concentration of 1.times.10.sup.-2 mol/L; adding 0.48
mL 1.times.10.sup.-2mol/L sodium borohydride aqueous solution
rapidly into the palladium chloride aqueous solution under the
magnetic stirring condition, and then continuing to react for 20
min to obtain 10 mL Pd nanoparticle sol with the Pd concentration
at 1.times.10.sup.-4mol/L; then adding 0.5 g PVP into this 10 mL Pd
nanoparticle sol, and magnetically stirring for 4 h to produce the
Pd nanoparticle having been subject to the surface treatment.
[0045] Preparation of 0.01 mol Sr.sub.2CeO.sub.4:1.times.10.sup.-5
Pd: Putting 10 mL 2 mol/L Sr(NO.sub.3).sub.2 solution and 10 mL 1
mol/L Ce(NO.sub.3).sub.3 solution into a beaker, then adding 20 mL
ethanol, and stirring sufficiently to obtain a mixed nitrate
solution; adding into this mixed solution 18.9126 g citric acid
(the molar ratio of the added citric acid to the total metal ions
in the mixed solution is 3:1) and 1 g PEG (polyethylene glycol),
and stirring sufficiently; taking 1 mL of the above metal particle
solution having been processed, and heating and stirring at
90.degree. C. in a water bath for 2 h to produce a sol; drying the
sol completely at 150.degree. C. to produce the precursor; putting
this precursor in a high temperature furnace, presintering at
800.degree. C. for 2 h, cooling to the room temperature, and
grinding; then putting it in a box type high temperature furnace or
tubular furnace, calcining at 1300.degree. C. for 2 h, naturally
cooling, and grinding to produce the
Sr.sub.2CeO.sub.4:1.times.10.sup.-5Pd luminescent material.
EXAMPLE 5
[0046] Preparation of the Pt/Au nanoparticle sol: Weighing 6.2 mg
chloroauric acid (AuCl.sub.3.HCl.4H.sub.2O) and 7.8 mg
chloroplatinic acid (H.sub.2PtCl.sub.6.6H.sub.2O) to dissolve into
28 mL deionized water to obtain a mixed solution of chloroauric
acid and chloroplatinic acid; after dissolving completely, weighing
22 mg sodium citrate and 20 mg PVP, and dissolving into the above
mixed solution under the magnetic stirring condition; weighing 5.7
mg of the newly prepared sodium borohydride to dissolve into 10 mL
deionized water to obtain 10 mL sodium borohydride aqueous solution
at a concentration of 1.5.times.10.sup.-2 mol/L; adding 2 mL
1.5.times.10.sup.-2 mol/L sodium borohydride aqueous solution into
the above mixed solution at one time under the magnetic stirring
condition, and then continuing to react for 20 min to obtain 30 mL
Pt/Au nanoparticle sol with the total metal concentration at
1.times.10.sup.-3 mol/L; adding 2 g PVP into the Pt/Au nanoparticle
sol, and magnetically stirring for 6 h to produce the Pt/Au
nanoparticle having been subject to the surface treatment.
[0047] Preparation of 0.01 mol
Sr.sub.2CeO.sub.4:1.times.10.sup.-3Pt/Au: Putting 10 mL 2 mol/L
Sr(NO.sub.3).sub.2 solution and 10 mL 1 mol/L Ce(NO.sub.3).sub.3
solution into a beaker, then adding 20 mL ethanol, and stirring
sufficiently to obtain a mixed nitrate solution; adding into this
mixed solution 18.9126 g citric acid (the molar ratio of the added
citric acid to the total metal ions in the mixed solution is 3:1)
and 1 g PEG (polyethylene glycol), and stirring sufficiently;
taking 10 mL of the above metal particle solution having been
processed, and heating and stirring at 80.degree. C. in a water
bath for 5 h to produce a sol; drying the sol completely at
100.degree. C. to produce the precursor; putting this precursor in
a high temperature furnace, presintering at 500.degree. C. for 5 h,
cooling to the room temperature, and grinding; then putting it in a
box type high temperature furnace or tubular furnace, calcining at
1000.degree. C. for 3 h, naturally cooling, and grinding to produce
the Sr.sub.2CeO.sub.4:1.times.10.sup.-3Pt/Au luminescent
material.
[0048] The above strontium cerate luminescent material of the oxide
system has good stability and, with the luminescent material doped
with metal particles, improved luminous intensity by making use of
the surface plasmon resonance generated by surface of the metal
particles; besides, the doped metal ion can improve electrical
conductivity of the luminescent material, and guarantee that the
luminescent material has higher brightness in field emission
devices or LEDs.
[0049] In addition, the strontium cerate luminescent material
prepared by the above method has stable properties and high
luminous efficiency, and the preparation method has the advantages
of simple operation, no pollution, easy control, low requirements
for equipment, and being favorable to industrialized
production.
[0050] The above examples only show several embodiments of the
present invention. Although they are described specifically and in
detail, they cannot be comprehended as restriction of the scope of
the present invention patent. For those of ordinary skill in the
art, it should be indicated that some deformation and improvement
could also be made without departing from the concept of the
present invention, and all fall within the scope of protection of
the present invention. Therefore, the scope of protection of the
present invention patent shall be determined by the appended
claims.
* * * * *